The present invention relates to compressors used in, for example, air conditioners mounted on vehicles, and, more specifically, to structures for collecting oil leaking from the interior of the compressors.
A typical compressor is described, for example, in Japanese Unexamined Utility Model Publication No. 55-39328. Specifically, as shown in FIG. 5, a drive shaft 51 is supported by a housing 52 accommodating a compressing mechanism. The drive shaft 51 is connected with the compressing mechanism while a portion of the shaft 51 projects from the housing 52. A boss portion 53 is arranged along an outer wall of the housing 52 such that the boss portion 53 encompasses the projecting end of the drive shaft 51. A seal 54 is arranged between the boss portion 53 and the drive shaft 51, thus sealing the housing 52. An electromagnetic clutch 55 includes a rotor 56, which is rotationally supported by the boss portion 53. An armature 57 of the electromagnetic clutch 55 is secured to the projecting end of the drive shaft 51 by a hub 58.
When a core 59 arranged near the rotor 56 is excited, the armature 57 is pressed against the rotor 56. The drive force of the vehicle engine is thus transmitted to the drive shaft 51. The drive shaft is then rotated to activate the compressing mechanism, and refrigerant gas is compressed.
In the above compressor, heat is generated by friction between the drive shaft 51, which is continuously rotated, and the seal 54. The heat hardens the seal. Furthermore, the seal deteriorates over time, and foreign objects may be caught by the seal. The performance of the seal 54 is thus lowered, and lubricant oil in the housing 52 leaks to the exterior of the housing 52 through an opening 53.alpha. of the boss portion 53. The lubricant oil adheres to, for example, the opposed surfaces of the armature 57 and the rotor 56. Thus, the armature 57 slips on the rotor 56, and the power transmitting efficiency is lowered.
Therefore, the compressor described in Japanese Unexamined Utility Model Publication No. 55-39328 includes a ring stopper 60 arranged along the inner side of the boss portion 53. The ring stopper 60 is located between the seal 54 and the opening 53.alpha. of the boss portion 53. The stopper 60 stops lubricant oil moving along the inner surface of the boss portion 53 toward the opening 53.alpha.. An oil absorber 61 is held by the housing 52. The boss portion 53 has an interior space from which an oil passage 62 extends to the oil absorber 61. The oil passage 62 has an opening located at a position corresponding to the inner side of the boss portion 53 and between the stopper 60 and the seal 54. Thus, the lubricant oil stopped by the stopper 60 is guided by the oil passage 62 to the oil absorber 61. The oil is then absorbed by the oil absorber 61.
However, some lubricant oil forms a film and moves along the surface of the drive shaft 51. Furthermore, a clearance is defined between the drive shaft 51 and the stopper 60 so that no sliding resistance is caused between the stopper 60 and the shaft 51. Thus, in the above described compressor, the lubricant oil moving along the surface of the drive shaft 51 is not guided to the oil absorber 61 and does not escape from the drive shaft 51 into the space between the stopper 60 and the seal 54.
To solve this problem, for example, Japanese Unexamined Utility Model Publication No. 1-124394 describes an arrangement of a ring 63, as indicated by the double dotted chain line in FIG. 5. The ring 63 extends along the surface of the drive shaft 51 at a position corresponding to the space between the stopper 60 and the seal 54. The ring 63 stops the lubricant oil moving along the surface of the drive shaft 51. Centrifugal force urges this lubricant oil to enter the space between the stopper 60 and the seal 54.
However, the compressor described in Japanese Unexamined Utility Model Publication No. 1-124394 has the following problems:
(1) The ring 63 must be formed independently from the drive shaft 51. The number of the compressor parts thus increases.
(2) When assembling the compressor, the ring 63 must be fitted onto the drive shaft 51. The number of the assembly steps thus increases. Furthermore, the assembly must be performed in a restricted order. Specifically, the seal 54 must be placed at a predetermined position between the drive shaft 51 and the boss portion 53 before attaching the ring 63 around the drive shaft 51. In other words, the drive shaft 51 must be inserted in the housing 52 without the ring 63. Thus, the ring 63 must be fitted to the drive shaft 51 within the interior space of the boss portion 53, which is limited, and the assembly is complicated.
(3) The ring 63, which projects toward the inner side of the boss portion 53, shields the seal 54 from the exterior of the housing 52. The temperature thus increases in the vicinity of the seal 54, which deteriorates the seal 54.